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KWA M4A1 loss of FPS


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#1 Ur-enation

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Posted 25 October 2008 - 06:02 AM

I have a KWA M4A1 that is about 5 months old, but I have around 40,000 rounds through it. I have used 9.6v, 10.8v and recently, two different 11.1v batteries with this gun. With the 9.6 and 10.8 batteries, I never had an issue. Witht the lipos, one was a 12c and the other is a 20c. I have been using the 20c for about a month and my gun was shooting 365-372 fps with .25 bb's. The only mod I did too the gun was change the barrel to a Madbull 6.03 TB.
Last week during the last game, I noticed that my gun lost range and I kept adjusting my hop up. I couldn"t hit targets at certain distances that I normally could. I had my  gun chrono'd last night and it was shooting 365 with .20 bb's, but the ROF is still 24 per second.
Can anyone tell me what I broke? I suspect it has something to do with the piston? Or maybe the spring is worn down from the compression stress of the 20c battery.
Any help would be appreciated. I LOVE my M4!! But I need to get my gun ready for an Op coming up in 2 weeks. Any suggestions?

Thanks,

#2 Blacssr@bellsouth.net

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Posted 25 October 2008 - 06:28 AM

View PostUr-enation, on Oct 25 2008, 10:02 AM, said:

I have a KWA M4A1 that is about 5 months old, but I have around 40,000 rounds through it. I have used 9.6v, 10.8v and recently, two different 11.1v batteries with this gun. With the 9.6 and 10.8 batteries, I never had an issue. Witht the lipos, one was a 12c and the other is a 20c. I have been using the 20c for about a month and my gun was shooting 365-372 fps with .25 bb's. The only mod I did too the gun was change the barrel to a Madbull 6.03 TB.
Last week during the last game, I noticed that my gun lost range and I kept adjusting my hop up. I couldn"t hit targets at certain distances that I normally could. I had my  gun chrono'd last night and it was shooting 365 with .20 bb's, but the ROF is still 24 per second.
Can anyone tell me what I broke? I suspect it has something to do with the piston? Or maybe the spring is worn down from the compression stress of the 20c battery.
Any help would be appreciated. I LOVE my M4!! But I need to get my gun ready for an Op coming up in 2 weeks. Any suggestions?

Thanks,

The spring has weakened from use. I change/replace mine every 20k -25k rounds, clean and lube gearbox. Takes about 20 minutes or so. Keeps guns up to speed

#3 brooklyn468

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Posted 25 October 2008 - 08:23 AM

Your LiPo is above the reccommended discharge rate. Yours is at 20c and the highest one you should get would be an 18c.

#4 vic_man4

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Posted 25 October 2008 - 12:11 PM

View PostUr-enation, on Oct 25 2008, 06:02 AM, said:

I have a KWA M4A1 that is about 5 months old, but I have around 40,000 rounds through it. I have used 9.6v, 10.8v and recently, two different 11.1v batteries with this gun. With the 9.6 and 10.8 batteries, I never had an issue. Witht the lipos, one was a 12c and the other is a 20c. I have been using the 20c for about a month and my gun was shooting 365-372 fps with .25 bb's. The only mod I did too the gun was change the barrel to a Madbull 6.03 TB.
Last week during the last game, I noticed that my gun lost range and I kept adjusting my hop up. I couldn"t hit targets at certain distances that I normally could. I had my  gun chrono'd last night and it was shooting 365 with .20 bb's, but the ROF is still 24 per second.
Can anyone tell me what I broke? I suspect it has something to do with the piston? Or maybe the spring is worn down from the compression stress of the 20c battery.
Any help would be appreciated. I LOVE my M4!! But I need to get my gun ready for an Op coming up in 2 weeks. Any suggestions?

Thanks,

Maybe your O-ring is shot or your losing air through a bad seal. I would suggest shooting your gun while it is split in half and putting your hand infront of the air nozzle to see if sufficient air is coming out.

#5 triple b

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Posted 25 October 2008 - 12:41 PM

could be a bad hop bucking or torn hop bucking.....

#6 Ur-enation

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Posted 25 October 2008 - 08:50 PM

View Posttriple b, on Oct 25 2008, 01:41 PM, said:

could be a bad hop bucking or torn hop bucking.....
I just wanted to thank everyone for your responses.

I have taken apart and changed parts for my Echo1 G36 and E1 M16 A4 gearboxes, but I have never taken apart my KWA. I am a little worried, because this gun is my baby.

I do think the problem has to do with compression, since I am still shooting 24 rps. Perhaps the stress from the lipo battery has either dried up the gear box lube, creating a bit of resistance or maybe the hop up bucking needs to be changed. Or perhaps the spring does need to be changed. I'll have to check it out.

Thanks again to all of your support.

Ur-enation

#7 Blacssr@bellsouth.net

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Posted 25 October 2008 - 10:06 PM

View Postbrooklyn468, on Oct 25 2008, 12:23 PM, said:

Your LiPo is above the reccommended discharge rate. Yours is at 20c and the highest one you should get would be an 18c.

What does this have to do with his loss of FPS? I have been running 25c for months.

#8 Blacssr@bellsouth.net

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Posted 25 October 2008 - 10:29 PM

View Postvic_man4, on Oct 25 2008, 04:11 PM, said:

Maybe your O-ring is shot or your losing air through a bad seal. I would suggest shooting your gun while it is split in half and putting your hand infront of the air nozzle to see if sufficient air is coming out.

How would he measure the air pressure? By feel? Not a very scientific method.;-)

#9 brooklyn468

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Posted 26 October 2008 - 02:38 PM

View PostBlacssr@bellsouth.net, on Oct 26 2008, 01:06 AM, said:

What does this have to do with his loss of FPS? I have been running 25c for months.

It could ware something down. I was just pointing it out.

25c is really not good for your motor, by the way.

#10 Ur-enation

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Posted 27 October 2008 - 07:03 AM

View Postbrooklyn468, on Oct 26 2008, 03:38 PM, said:

It could ware something down. I was just pointing it out.

25c is really not good for your motor, by the way.

I agree. I will be changing back to my 10.8v 2000mah battery. The high amp output of the 20-25c battery puts way more stress on the gun than it was designed to handle. The internal parts wear out at a faster rate than those with lower amp output batteries.
I am going to take it all apart to see which parts are worn and replace them.

#11 vic_man4

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Posted 27 October 2008 - 05:40 PM

View PostBlacssr@bellsouth.net, on Oct 25 2008, 10:29 PM, said:

How would he measure the air pressure? By feel? Not a very scientific method.;-)

Yeah but if its a quick spurt of air then you should get an idea of what is wrong barrel-bucking or gearbox, it narrows it down a bit, I find it helps a lot.

#12 M17

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Posted 27 October 2008 - 06:45 PM

View PostBlacssr@bellsouth.net, on Oct 25 2008, 07:28 AM, said:

The spring has weakened from use. I change/replace mine every 20k -25k rounds, clean and lube gearbox. Takes about 20 minutes or so. Keeps guns up to speed

Wait wait wait wait, it takes about 20 minutes to open up your gun and clean it, it takes more like an hour and a half.

#13 brooklyn468

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Posted 27 October 2008 - 06:48 PM

View PostM17, on Oct 27 2008, 09:45 PM, said:

Wait wait wait wait, it takes about 20 minutes to open up your gun and clean it, it takes more like an hour and a half.

It depends on your experience ;)

#14 triple b

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Posted 27 October 2008 - 10:54 PM

it take 2 mins to open the gun to look at the bucking.......really its only one bolt

#15 M17

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Posted 29 October 2008 - 01:46 PM

View Postbrooklyn468, on Oct 27 2008, 07:48 PM, said:

It depends on your experience ;)

Ya but how throe do you clean it because i make my gears and everything else spotless when i put it back together.

#16 Stealthmaster14

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Posted 29 October 2008 - 02:01 PM

If you are talking about your gearbox, you don't want it spotless.  Grease is their for a reason ;)

#17 M17

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Posted 29 October 2008 - 02:10 PM

View PostStealthmaster14, on Oct 29 2008, 03:01 PM, said:

If you are talking about your gearbox, you don't want it spotless.  Grease is their for a reason ;)

I know that of coarse i put grease in it. lithium grease

#18 triple b

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Posted 29 October 2008 - 03:10 PM

its metal..... idk maybe use some gun cleaner or regular degreaser from an auto parts store?

#19 Stealthmaster14

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Posted 29 October 2008 - 03:16 PM

View Posttriple b, on Oct 29 2008, 04:10 PM, said:

its metal..... idk maybe use some gun cleaner or regular degreaser from an auto parts store?

From what I've read, you are NEVER supposed to use real steel cleaning products on an airsoft gun.  

To the OP, check your bucking and if that's not it, you will need to crack open your gearbox. (not literally lol)  Until you do that, we can't help you

Edited by Stealthmaster14, 29 October 2008 - 03:16 PM.


#20 Guest_allizard_*

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Posted 29 October 2008 - 11:07 PM

View PostStealthmaster14, on Oct 29 2008, 04:16 PM, said:

From what I've read, you are NEVER supposed to use real steel cleaning products on an airsoft gun.  

To the OP, check your bucking and if that's not it, you will need to crack open your gearbox. (not literally lol)  Until you do that, we can't help you

Humm.... we did that all the time.




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